Structure – Performance relationship of tertiary amines for CO2 Capture & Carbon Mineralization (CCMC)

The amine-based CO 2 capture & mineral carbonation (CCMC) using alkaline slag represents a promising decarbonation strategy. While prior studies have shown the type of amine as a critical factor for CO 2 absorption and mineralization kinetics, their molecular structural effects remain underexplored. This work combines experiments with density functional theory (DFT) calculations to systematically investigate the structure–performance relationship of tertiary amines in coupled CO 2 capture and mineral carbonation, focusing on calcium conversion, apparent mineralization kinetics, and CaCO 3 product characteristics to inform rational amine selection and design. Specially, this work evaluates how selected properties of tertiary amine structures, i.e., length of the carbon chain, number of hydroxyl and amine groups, presence cyclic frameworks, impact CCMC efficiency. Experimental and quantum chemical analyses reveal that the apparent CCMC rate generally increased with amine basicity. Within the TREA–DEEA–EDEA–TEA series, increasing hydroxyl substitution decreased proton affinity, initial solution pH, and calcium-conversion rate. While steric hindrance and hydrogen bonding show negligible impacts. Surprisingly, the presence of additional amine groups does not boost reactivity due to unfavorable secondary protonation energetics. Interestingly, the interactive energy term proton affinity showed a broad correlation with the apparent calcium-conversion trend for elucidating the amine property – performance relationship in CO 2 capture. These findings provide a mechanistic framework for designing tertiary amines to optimize carbon capture kinetics and product purity, with implications for scalable industrial deployment.